we explain why the return of the El Niño weather phenomenon is feared

Meteorologists and climatologists around the world are on the alert. “A significant evolution of the planetary climate system is taking place this summer with the probable emergence of the El Niño phenomenon”, writes Météo France, Monday, April 24, in its three-month forecast. Some scenarios even anticipate a “super El Niño” to come. Franceinfo returns to this meteorological phenomenon to try to see it clearly.

What is El Niño?

This is a meteorological phenomenon that results in an increase in the temperature of the surface of the water in the eastern Pacific. It occurs cyclically but irregularly, every three to seven years, and causes climatic disasters, in particular dry spells and above-normal rainfall.

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The phenomenon generally reaches its maximum intensity towards the end of the year, hence the name El Niño, which also designates the child Jesus, in Spanish. Its impact is global, explains to France 24 Jérôme Vialard, oceanographer and research director at the Research Institute for Development.

“It’s such a powerful phenomenon that it’s influencing the climate all over the globe.”

Jérôme Vialard, oceanographer

at France 24

France Télévisions journalist Nicolas Chateauneuf presented the phenomenon in 2016, on the set of France 2’s “20 Heures”. He then explained that with El Niño, the heat of the equatorial Pacific was not pushed towards Asia and Australia, but remained rather close to Latin America.

El Niño is to be differentiated from La Niña, which tends to lower the temperature of the oceans. According to the World Meteorological Organization (WMO), this phenomenon is coming to an end. Ongoing since 2020, this episode has been “exceptionally long and persistent”, notes the WMO. Generally, we observe an alternation between La Niña and El Niño with, in between, neutral conditions.

What do we know about his return?

Nothing is certain. We are still at the probability stage. But they lean towards a return of El Niño. “Today, we are already observing strong climatic signals, which show a significant warming of the equatorial Pacific Ocean”explains to New Caledonia La 1ère Thomas Abinun, climatologist at Météo France.

“It’s a signal that we are monitoring, because this warming of the ocean could lead to the occurrence of an El Niño episode, from the second half of the year.”

Thomas Abinun, climatologist at Météo France

in New Caledonia The 1st

This observation is shared across the entire planet. According to the WMO, the chances of El Niño developing are estimated at 15% in April-June, 35% in May-July and 55% in June-August. For its part, the American Agency for Oceanic and Atmospheric Observation (NOAA) writes, in its follow-up bulletin published on April 24 (PDF in English), that there is a 62% chance that the phenomenon will reappear by the summer. A figure that is close to 90% by the end of the year.

“You can compare it to a loaded gunsummarized with the British daily The Guardian Axel Timmermann, climate specialist at the University of Busan (South Korea). “The magazine is full but the atmosphere hasn’t pulled the trigger yet.”

But why do we speak of a potential “super El Niño”?

The Australian Bureau of Meteorology reports that some forecast models suggest the possible occurrence of a “super El Niño” for this year. If the classic phenomenon corresponds to an increase in the temperature of the equatorial Pacific of 0.8°C compared to normal, a “super El Niño” is characterized by an increase of at least 2°C. These higher temperatures would result in more powerful effects.

Such a phenomenon is rare. Specialists only count three over the past forty years: 1982-1983, 1997-1998 and 2015-2016. “Temperatures in 2016 and, to a lesser extent, in 2015, were pushed up by an exceptionally strong El Niño phenomenon”reported in 2017 the World Meteorological Organization (WMO).

However, the high level of uncertainty must be underlined and all the scenarios mentioned must be taken with great caution. “We need two or three more months to have a more reliable idea of ​​what will follow”warned Alvaro Silva, consultant at WMO.

What could be the consequences for the global climate?

Impossible to be precise at this stage. El Nino “risk of fueling a new peak in global temperatures”, says Petteri Taalas, the secretary general of the WMO. The previous episodes had raised the mercury all over the world. We must therefore expect the same consequences, especially since the last eight years (2015-2022) have already been the hottest ever recorded on the planet, while La Niña tends to lower the temperature of the oceans.

If these are natural phenomena, the WMO recalls that El Niño and La Niña are part of “against the backdrop of human-induced climate change, which is raising global temperatures, affecting seasonal rainfall patterns and making our climate more extreme”. In other words, the phenomenon predicted for the year 2023 will only add to the global warming of human origin, a warming so strong that even La Niña has not managed to fade it.

Beyond the global increase in temperatures, the consequences linked to El Niño are different depending on the areas of the globe. For South America, it may be torrential rains with the risk of landslides and an ocean that no longer allows fishermen to live. On the Australian side, the phenomenon could induce an increased risk of drought, also increasing the risk of fires. The problem of drought also concerns the African continent and part of Asia with a potential drop in agricultural yields and an increase in the risk of famine. WMO already illustrated all these consequences in a video published seven years ago.

A potential “super El Niño” combined with the current acceleration of global warming could therefore have even greater consequences. This is why monitoring is meticulous. “Tracking the swing between the two phases helps countries prepare for their potential impacts”explains the WMO.